Smoke filters

ABSTRACT

A filter for a cigarette or other smoker&#39;&#39;s article wherein loose material is held in separate layers by porous elements arranged between the layers and so arranged that smoke passing from one end of the filter to the other is constrained to pass across and through said layers in succession.

ted States Patent 1 Labhc Sept. 11, 1973 SMOKE FILTERS [56] ReferencesCited [75] Inventor: Francis Auguste Maurice Labbe, UNITED STATES PATENTS Neuilly-sur-Seine, France 2,164,702 7/1939 Davidson 93/1 C 4 55 M"ll [731 Asslgnee: Mach-m Company 3372 339 1311323 8585,26 953%,?

London, England [22] Filed: Oct. 13, 1971 Primary Examiner-Andrew R. Juhasz [211 App! 188374 Assistant ExaminerLeon Gilden Related U S.- A li atign Dam Attorney-Craig, Antonelli & Hill [62] Division of Ser. No. 880,747, Nov. 28, 1969,

abandoned.

[30] Foreign Application Priority Data 57] ABSTRACT Dec. 4, 1968 Great Britain.. 57763768 June 27, 1969 Great Britain ..32625/69 A filter for a cigarette or other smokers article wherein [52] US. Cl 93/1 C loose matena held m separate layers by Porous elements arranged between the layers and so arranged [51] Int. Cl. B3lc 5/00 that smoke passing from one end of the filter to the [58] Field of Search, 93/1 C, 12 C other 15 constrained to pass across and through said layers in succession.

5 Claims, 7 Drawing Figures W4 /ZZ /Z/ /6 A5 fig; a t //7 1 W fill K5 #5 L ;Q O

J W w U Q w w m5 0 PATENTEDSEPI 1 I975 SHEET 1 UF 2 PATENTEU SEP! 1 I975 SHEET 2 [IF 2 SMOKE FILTERS This is a division, of application Ser. No. 880,747 filed Nov. 28, 1969 now abandoned.

This invention concerns improvements in or relating to smoke filters for cigarettes or other smokers articles such as cigars.

Various proposals have been made, and some have been put into practice, for smoke filters of a composite nature containing granular, powdered or like material. Such a filter may take the form of a cylindrical tubular wrapping containing a stub (e.g., of paper or of cellulose acetate fibres) at each end, with granular or powdered material occupying the space between the stubs. Such a filteris usually joined to one end of a cigarette by an encircling band.

For convenience, granular, powered or like materials suitable for use in a filter will be called loose material.

A problem met with in connection with filters of this nature is the difficulty in ensuring that smoke drawn through the filter by the smoker passes through the loose material and does not by-pass it. Difficulty may .be encountered during manufacture of the filters in ensuring that the spaces between stubs are completely filled with loose material. Even if these difficulties are overcome and the spaces in newly made filters are well filled, it is not certain that they will remain equally well filled during the time that elapses until the filter cigarettes reach the customer. The handling and transporting of the filters before they are combined with ciga-- rettes, theaction of the machinery by which they are combined with cigarettes, and the handling and transporting of the filter cigarettes, may all affect the distribution of the loose material (if this material is at all compressible) by causing it to become more compact, and the more compressible the loose material, the greater is the risk of undesired compacting which may result in gaps through which the smoke can pass instead of passing wholly through the loose filtering material.

In the case of very compressible loose material, there is the further problem that when the smoker draws on the cigarette, the draught action produces alarge gradient of density along the body of material, resulting in an unacceptably large pressure drop which occurs mostly where the material is closely packed; the greater the volume of loose material through which smoke is drawn, the more acute this problem is likely to become.

In the case of finely powered material even if it is incompressible or nearly so, a high degree of compactness is needed to avoid the risk of smoke by-passing the material;.as a result, if the pressure drop across the material is to be kept at an acceptable level, it is found necessary to restrict the axial length of the space occupied by this material, with consequential reduction of filtering efficiency;

The present invention is, according to one aspect, concerned with filters embodying loose materials.

The invention provides a filter for a cigarette or other smokers article wherein loose material is held in separate layers by porous elements arranged between the layers and so arranged that smoke passing from one end of the filter to. the other is constrained to pass across and through said layers in succession.

The invention further providesa filter for a cigarette or other smoker's article whereina tubular wrapper encloses a plug comprising a series of porous disc-like elements which hold between them separate layers of loose material and which are disposed in planes transverse to the axis of filter, so that smoke is constrained to pass across and through said layers while flowing axially of the filter.

The invention further provides a filter for a cigarette or like smokers article, incorporating loose material, in which the loose material is contained within a tubular chamber, and comprising a smoke inlet at one end of the chamber and a smoke outlet at the other end of the chamber, the outlet being radially displaced from the inlet so that smoke passing from the inlet to the outlet is constrained to flow in substantially radial directions through the loose material.

The invention further provides a filter for a cigarette or other smokers article in which a tubular wrapper encloses, a plug of porous paper or the like, folded or otherwise arranged to present a multitude of layers extending lengthwise of the filter and arranged substantially concentrically, the layers containing between them layers of loose material, and in which smoke passing from one end of the filter to the other is constrained to flow in a substantially radial direction, either outwardly or inwardlyjacross and through 'the'substan tially concentric layers in succession.

For example, the filter can contain sealing members at opposite ends of the plug, one of which allows smoke to pass only through a central aperture which communicates with a central, axially extending channel in the plug, while the other sealing member allows smoke to pass only through an annular channel or channels at its periphery (e.g., between its periphery and the inner surface of the tubular-wrapper) communicating with one or more annular, axially extending, outer channels or spaces between the tubular wrapper and the outermost layer or layers of the plug. Thus smoke entering at one end can escape through the other end only by flowing more or less radially across the successive alternating layers of porous material and loose material, either from the central to the outer channels or from the outer to the central channel, depending on the disposition of the filter in relation to the direction, of flow. As each layer of loose material is thin, and as the smoke is drawn through each layer in succession, little significant compacting of the loose material can occur; moreover each layer of loose material is held between layers of porous paper or the like which prevent any significant displacement of the loose material such as would enable smoke to by-pass it.

The present invention is also concerned with a rod making machine which can construct a filter having a non-axial filtering path.

According to the present invention apparatus for forming a continuous filter rod comprises means to form at least two axial passages through a filter rod and means to seal only one end of each passage to form a non-axial smoke path through the filter rod;

According to the present invention apparatus for manufacturing a continuous filter rod comprises:

a. means to secure discrete seal elements to a continuous porous web at spaced intervals along its length;

b. means to deposit finely divided filter material on to the continuous porous web;

c.means ,to cut the porous web longitudinally into a plurality of strips;

d. means to stack the said plurality of strips one on top of the other;

e. means to fold the stacked strips into a plurality of concentric tubes to form a cylinder, the concentric tubes being spaced radially from one another by some of the seal elements and the central bore of the cylinder being closed at intervals along its length by others of the seal elements; and

f. means for forming a continuous outer wrapper around the cylinder so that the outer wrapper is spaced from the cylinder by the said some seal elements to provide an annular space between the cylinder and the wrapper.

According to one aspect of the invention means are provided for forming indentations in the said wrapper web, the indentations serving to locate the cylinder laterally in those positions where there is no seal to do this.

According to the present invention a method of manufacturing a continuous filter rod comprises the following steps:

a. securing discrete seal elements to a continuous porous web at spaced intervals along its length;

b. depositing finely divided filter material onto the continuous porous web;

c. cutting the porous web longitudinally into a plurality of strips which are then stacked one on top of the other;

d. folding the stacked strips into a plurality of concentric tubes to form a cylinder, the concentric tubes being spaced radially from one another by some of the seal elements and the central bore of the cylinder being closed at intervals along its length by others of the seal elements; and

e. forming a continuous outer wrapper around the cylinder and spacing it from the cylinder by the said some seal elements to provide an annular space between the cylinder and the wrapper.

According to the present invention a filter plug comprises the following elements in combination:

a. a plurality of concentric tubes of porous material are spaced apart radially from one another and finely divided filter material is located in their interstices;

b. a plurality of bands are located at each end of the tubes and each band is positioned in an interstice between two adjacent tubes to space the two tubes radially apart from one another;

c. a plug seals one end of the central bore running through the radially innermost tube; and

d. the outermost tube is enclosed in a tubular wrapper which at one end of the filter is spaced from the outermost tube by means which will allow the passage of smoke between the outermost tube and the outer wrapper and at the other end of the filter the space between the outermost tube and the outer wrapper is blocked by an annular seal.

How the invention may be carried out will now be described by way of example only, with reference to the accompanying drawings in which:

FIG. I is a diagrammatic sectional view ofa filter associated with a cigarette;

FIG. 2 is a view, greatly enlarged, of a fragment of FIG. 1;

FIG. 3 shows a modification of the filter shown in FIG. 1;

FIG. 4 shows another form of filter;

FIG. 5 is an enlarged fragmentary view ofa filter similar to that shown in FIG. 1; and

FIGS. 6 and 7 illustrate diagrammatically the method and apparatus for producing the filter shown in FIG. 5.

Referring first to FIG. 1, the filter shown abutted against the end of a cigarette portion 1, comprises a plug 2 consisting of porous paper or the like, folded, wound or otherwise arranged in a multitude of layers 3 (see FIG. 2) which extend lengthwise of the filter and are arranged substantially concentrically; layers of loose material 4 contained and held between the porous layers 3; sealing elements 5 and 6 at opposite ends of the plug; and end stub 7 which may be a conventional filter element, e.g., made of paper or cellulose acetate fibres; and a tubular wrapper 8 enclosing these components.

The plug 2 has a central axially extending channel 9, and there is an annular, axially extending channel or space 10 between the tubular wrapper 8 and the outermost layers of the plug. These channels may be substantially hollow and empty, or may contain spacing elements such as axially extending ribs, or may contain porous material through which smoke can flow freely lengthwise of the filter.

The sealing elements Sand 6, shown for clarity in the drawing are of substantial thickness, can be relatively thin and of any material suitable for sealing the ends of the plug 2. The element 5 has a central aperture 11 which communicates directly with the central channel 9 on the one hand, and with the interior of the cigarette portions, on the other hand. The outer edge of the element 5 makes sealing contact with the tubular wrapper 8. The element 6 is provided at its periphery with annularspaces or channels 12 communicating directly with the annular channel or space 10 on the one hand, and on the other hand with a chamber 13 between the element 6 and the end stub 7.

This construction ensures that substantially all the smoke drawn from the cigarette through the filter into the smokers mouth is constrained to flow across and through the layers 3 of porous material and the layers 4 of loose material held therebetween, in generally radial directions. The directions followed by the smoke are indicated generally by the arrows in FIG. 1. Smoke can enter the plug 2 only through the central aperture 1 1, and can leave it only through the spaces or channels 10. Thus the elements 5 and 6, with the tubular wrapper 8, define a tubular chamber containing loose material and through which smoke is constrained to-flow in substantially radial directions.

The disposition of the elements 5 and 6 could be reversed, so that the smoke is constrained to flow radially inwardly, instead of outwardly as shown in FIG. 1.

By an arrangement such as illustrated in FIG. 1 (or modified as just mentioned) it is possible to ensure that the smoke flows through an adequate quantity of loose material without increasing the pressure drop to an unacceptable degree, since the smoke passes through successive thin layers of the material in which little if any significant compression can occur; moreover displacement of the loose material to an extent such as to enable the smoke to by-pass it can be avoided since it is held between the layers of porous paper or like material.

In contrast to known filters incorporating loose material, the pressure drop across the filter according to the invention can be reduced by increasing the length of the plug in which the loose material is held, since this increases the area of the surfaces across which the smoke can flow.

FIG. 3 shows a modified construction in which two plugs 2 are provided in series, separated by a sealing element 26 like the element 6 in FIG. 1, and with an element 25, like the element 5 in FIG. 1, at opposite ends. The path of the smoke through this composite construction is indicated by arrows. In this modified construction, the central sealing element 26 could be replaced by an element 25 with a central aperture, the elements 25 shown at opposite ends being replaced by two elements like the element 26.

The porous paper or the like which forms the layers 3 can be corrugated, knurled, or otherwise roughened in order to assist in holding the loose material against displacement.

FIG. 4 shows another construction in accordance with the invention. In this construction loose material 4 is held between discs 23 of porous material such as porous paper, which are corrugated, knurled or otherwise deformed so as to hold the loose material against displacement. The discs 23 are disposed in an axially extending array between two conventional stubs 27 and the peripheral edges of the discs make sealing contact with the tubular wrapper 28.

It will be seen that in this construction smoke drawn from the cigarette portion 1 flows in a generally axial direction through the filter across and through successive thin layers of loose material held between the porous discs 23.-

In all the above described embodiments it will be understood that the filter and the cigarette portion are joined in endwise abutment by an encircling band which covers all or a part of the filter and extends over part of the cigarette portion; this encircling band is not shown in the drawings since it is a well known feature of filter cigarettes.

Referring to FIG. 5 this shows a fragmentary length of a continuous filter rod constructed by the machine shown in FIG. 6. The filter rod comprises an outer wrapper 101 of thin paper which surrounds a paper tube 102. Concentric tubes of porous support paper 103 are immediately enclosed in a thin porous paper 109 and are contained within the wrapper 101 and tube 102. The concentric porous paper tubes support finely divided filter material in their interstices. An axial bore 104 runs through the concentric tubes of porous paper 103.

At intervals along their lengths, equal to a plug length, the porous paper tubes 103 carry an annulus of concentric rings of thick paper 105.

Alternate concentric rings of paper 105 have a band of soft paper 106 located between the outermost ring and the tube 102.

The other alternate concentric rings of paper 105 have their outermost ring contacted by dimples 107 formed in the tube 102 in order to locate those alternate concentric rings of paper 105 against lateral movement.These same rings have a stub 108 of nonporous material contained within their innermost memher, the stub 108 blocking the axial passage 104.

The continuous rod, of which the portion illustrated in FIG. 5 forms a part, is cut through each annulus of concentric rings 105 at their mid points as shown by the chain dotted lines AA.

A filter plug thus formed will have a smoke passage illustrated by the arrowed path; the directions of the arrows could of course be reversed.

Apparatus for producing a filter rod constructed in accordance with FIG. 5 will now be described with reference to FIG. 6 in which the same reference numerals have been used to denote those parts of the apparatus which form or supply corresponding elements in the continuous filter rod shown in FIG. 5.

The upstream side of the apparatus is to the right of FIG. 6 and the downstream side to the left.

A web of porous support paper 103 is fed into the machine at its extreme upstream end. Onto the underside of the web of porous support paper 103 are stuck nonporous stubs 108 at intervals equal to two filter plugs lengths and on the upperside of the web 103 are stuck strips of thick paper 105 at intervals equal to one filter plug length, alternate strips 105 being in register with a stub 108, as shown in FIG. 7. The strips 105 and stubs are held on the web 103 by an adhesive. The means to secure the strips 105 and stubs 108 on the web 103 at the regular intervals referred to is illustrated schematically at 110 and 111.

The web 103 then passes beneath a hopper 113 which operates to deposit finely divided, e.g., powdered or granular, filter material onto the web. The web 103, thus loaded with filter material, then passes through slitting apparatus 114 which cuts the web 103 longitudinally into six strips which have graduated widths suitable for forming the six concentric tubes 103 shown in FIG. 5.

The slit web 103 then passes through apparatus 115 which is designed to stack the six slit wets one on top of the other, the narrowest web of the six being on the top of the stack.

A web of thin porous paper 109 is then introduced beneath the stackof slit webs 103 and the paper 109 and webs 103 then pass through a paster 116 which deposits a line of paste along one edge of the thin porous paper web 109, and then into a folder 117 which forms the stack of porous paper 103 and the porous web 109 into a rod, the line of paste along the paper 109 then being heated by a heater 118 to seal the paper 109 around the slit webs 103.

The rod so formed is then enclosed in a stiff paper tube 102, with bands of soft paper 106 enclosing one alternate series of thick paper annulii 105 and the other alternate series of annulii 105 being gripped by dimpled portions 107 of the thick paper tube 102. These operations are effected by taking a web of thick paper 102 from a reel and passing it through a tipping apparatus 119. The tipping apparatus 119 is supplied with a strip of porous paper 106 which is then cut into strips by the tipping apparatus 119 and deposited on the web 102 and held there by adhesive. The web 102, with the strips of paper 106 adhered to it, then passes through two contra-rotating wheels 120 which are formed with projections on their periphery at predetermined spaced circumferential intervals so as to form the dimples 107 at lengths along the web 102 equal to two filter plug lengths as the web 102 passes between the wheels 120.

The web 102 then passes beneath the rod emanating from the heater 118 and the two then pass into a second combination of paster 121, folder 122 and heater 123 which operate to enclose the rod emanating from the previous heater 118 in the stiff paper 102 and also in a final outer wrapper 101 of thin paper, the wrapper 101 being stuck to itself along one of its edges to form the finished filter rod shown in FIG. 5.

The above described apparatus is designed for forming a filter which employs finely divided filtering material which it is essential to support against being unduly compressed for example as a result of the air drawn through the filter by the smoker. Such finely divided material will normally compress to such a degree, under the draw, as to cause it to have an unacceptable pressure drop across it and thus make the cigarette unsmokable. By employing a series of concentric fine porous tubes 103 which are spaced apart from one another by the annulii 105 a plurality of annular containers is in effect provided for the finely divided filtering material. With this arrangement, although each individual annulus of filtering material can be subject to radial compression under the draw effect, because the annulii are kept spaced apart by the porous cylinders 103 an excessive draw resistance or pressure drop through the filter material is prevented.

I claim:

1. Apparatus for making cigarette filters, comprising means for forming a continuous tubular filter element; means for feeding a continuous wrapper web towards the tubular filter element; means for securing spacer strips at regular intervals across the wrapper web as it approaches the tubular filter element; means for wrapping the wrapper web around the filter element, whereby the spacer strips space the wrapper web from the tubular filter element to form an annular space between the filter element and the surrounding wrapper; and means for cutting the continuous wrapped tubular filter element at regular intervals into sections each comprising at least one filter element unit surrounded by a section of wrapper web spaced from the filter element unit to define therewith an annular space, one end of which is closed by at least a part of one of the spacer strips; and including means for closing the bore of the tubular filter element unit at the end remote from the end of the annular space closed by the spacer strip.

2. Apparatus according to claim 1, including means for forming depressions in the continuous wrapper web as it approaches the tubular filter element, whereby the depressions space the wrapper web from the tubular filter element at regions remote from the spacer strips.

3. Apparatus according to claim 1 in which the means for forming a continuous tubular filter element comprise means for bending into tubular formation a laminate comprising at least one layer of particulate filter material sandwiched between webs of porous sheet material.

4. Apparatus for manufacturing a continuous filter rod comprising the following features in combination:

a. means to secure discrete seal elements to a continuous porous web at spaced intervals along its length;

b. means to deposit finely divided filter material on to the continuous porous web;

c. means to cut the porous web longitudinally into a plurality of strips;

d. means to stack the said plurality of strips one on top of the other;

e. means to fold the stacked strips into the plurality of concentric tubes to form a cylinder, the concentric tubes being spaced radially from one another by some of the seal elements and the central bore of the cylinder being closed at intervals along its length by others of the seal elements; and

f. means for forming a continuous outer wrapper around the cylinder so that the outer wrapper is spaced on the cylinder by the said some seal elements to provide an annular space between the cylinder and the wrapper.

5. Apparatus as claimed in claim 4 in which means are provided for forming indentations in the said wrapper web, the indentations serving to locate the cylinder laterally in those positions where there is no seal to do this.

l i i 

1. Apparatus for making cigarette filters, comprising means for forming a continuous tubular filter element; means for feeding a continuous wrapper web towards the tubular filter element; means for securing spacer strips at regular intervals across the wrapper web as it approaches the tubular filter element; means for wrapping the wrapper web around the filter element, whereby the spacer strips space the wrapper web from the tubular filter element to form an annular space between the filter element and the surrounding wrapper; and means for cutting the continuous wrapped tubular filter element at regular intervals into sections each comprising at least one filter element unit surrounded by a section of wrapper web spaced from the filter element unit to define therewith an annular space, one end of which is closed by at least a part of one of the spacer strips; and including means for closing the bore of the tubular filter element unit at the end remote from the end of the annular space closed by the spacer strip.
 2. Apparatus according to claim 1, including means for forming depressions in the continuous wrapper web as it approaches the tubular filter element, whereby the depressions space the wrapper web from the tubular filter element at regions remote from the spacer strips.
 3. Apparatus according to claim 1 in which the means for forming a continuous tubular filter element comprise means for bending into tubular formation a laminate comprising at least one layer of particulate filter material sandwiched between webs of porous sheet material.
 4. Apparatus for manufacturing a continuous filter rod comprising the following features in combination: a. means to secure discrete seal elements to a continuous porous web at spaced intervals along its length; b. means to deposit finely divided filter material on to the continuous porous web; c. means to cut the porous web longitudinally into a plurality of strips; d. means to stack the said plurality of strips one on top of the other; e. means to fold the stacked strips into the plurality oF concentric tubes to form a cylinder, the concentric tubes being spaced radially from one another by some of the seal elements and the central bore of the cylinder being closed at intervals along its length by others of the seal elements; and f. means for forming a continuous outer wrapper around the cylinder so that the outer wrapper is spaced on the cylinder by the said some seal elements to provide an annular space between the cylinder and the wrapper.
 5. Apparatus as claimed in claim 4 in which means are provided for forming indentations in the said wrapper web, the indentations serving to locate the cylinder laterally in those positions where there is no seal to do this. 